Question 10 The genotypes of the two parents would be A - VCE - SSCE Biology - Question 10 - 2002 - Paper 1

To determine the correct genotypes of the two parents, we need to examine the combinations of alleles presented in the options. Each parent can contribute either a dominant or a recessive allele for each trait, thus we evaluate:

• Option A: ppLl x PPLL - This combination includes a homozygous recessive for one trait and a homozygous dominant for the other, making it unlikely to result in the ratios observed.

• Option B: PpLl x PPLL - One parent is heterozygous for both traits; this is a valid option, but it includes one parent that is homozygous dominant, leading to potential skewed ratios.

• Option C: PpLl x PpLl - Both parents are heterozygous for both traits. This setup allows for all combinations of dominant and recessive alleles, thereby producing a 9:3:3:1 ratio seen in dihybrid crosses, which is consistent with expected outcomes in genetic ratios. This is indeed the most versatile and representative cross for typical Mendelian ratios.

• Option D: PPLL x PpLl - Similar to option B, this combination has a homozygous dominant parent with a heterozygous mate but may yield skewed ratios.

After analysis, the most accurate answer reflecting typical genetic principle outcomes is C: PpLl x PpLl.